Root architecture traits and genotypic responses of wheat at seedling stage to water-deficit stress

This study was aimed to identify genotypic differences in shoot growth rate and root architecture traits in response to water-deficit stress at early growth stages of wheat seedling, and to quantify relationships between genotypic variation in shoot physiological traits and root system architecture with a drought tolerance at several development stages. Eight bread wheat cultivars, namely Bam, Mahooti, Roshan, Tabbasi, Atrak, Falat, Shiraz and Qods, were grown in polyvinyl chloride tubes filled with soil in the greenhouse under well-watered and water-deficit stress conditions. Water stress elicited genotypic variation in root traits and shoot growth across cultivars. Drought stress decreased root architecture traits, with greater effects in drought-sensitive cultivars compared with those that were drought-tolerant. Branch root length was less influenced compared with seminal root length. We showed that cultivars Roshan and Bam were most tolerant to drought due to their shorter distance between the first branch root and the root tip, higher branch root length, longer seminal roots and higher stomatal conductance compared to the other cultivars. Positive relationship between root growth and shoot physiological responses was quantified upon drought stress, highlighting the role of leveraging more efficient root systems as a strategy to enhance resource uptake under water-deficit conditions. Thus, root growth responses can be used as a drought tolerance selection criterion at the seedling stage of employed genotypes.